1. Field of the Invention
The present invention relates to an improved chock for use with a loop sling by rock climbers.
2. Description of the Prior Art
The rapid increase in the number of rock climbers has focused attention upon the necessity of employing climbing methods which are not destructive to the climbing area. This has resulted in a change from the use of pitons whose placement and removal erode the rock, to the use of lightweight chocks, also often referred to as chockstones or nuts, which are adapted to be jammed into existing cracks in rock and are designed to be removed by pulling on the related sling away from the wedging direction.
In general, two types of slings are used. One comprises a loop of rope or webbing threaded through the chock and made endless by a knot to receive a carabiner and hence will be referred to herein as a "loop" sling. The other type, normally made from wire rope, comprises a single run of cable secured at an end to the chock as by having a swagged head socketed in the chock, and having its other end doubled back and secured by a suitable crimped fitting to form a terminal eye for receiving a carabiner. This type is commonly referred to as a "single cable" sling.
The idea of jamming objects into cracks is an old concept in mountaineering. The English discovered that machine nuts through which a loop sling was threaded could offer better protection than knots or stones, and this was the forerunner of the more sophisticated "nuts" used as chocks today.
To reduce the number of chocks required to be carried by a climber to provide for the various widths of cracks which might be encountered, "camming" chocks have come into use, and namely chocks which wedge by rotation, and hence, can function for a range of crack widths. A simple example is the T-shaped "Titon" marketed by Forrest Manufacturing, Ltd., Denver, Colo., in which the center stem (leg) of the tee is slotted to receive the sling and the two flange arms of the tee act, one as a fulcrum on one face of a crack, and the other as a rotating wedge against the opposite face responsive to a load exerted on the center stem via the sling. A more complicated example, is "Kirk's Kamms", marketed by Colorado Mountain Industries Corporation, Cincinnati, Ohio, which have a single cable sling permanently anchored in the chock and riding from its anchor point in an exposed groove along a straight wedge face which comprises part of the peripheral edge. The remainder of the edge is curved to provide a rolling edge varying in distance from the anchored end of the sling.
Another commonly used chock is the "Hexentric" marketed by the Great Pacific Iron Works, Ventura, Calif., which comprises a short length, beveled at its ends, of extruded aluminum stock having a hexagonal cross-section with all of its sides of different widths. Two of the sides of the hexagon are substantially parallel and have pairs of registering holes through which a loop sling is threaded such that the bight of the loop bears against the wider of the two sides when the loop is tensioned. A Hexcentric" is essentially a wedge, but will "cam" to a limited extent in parallel walled cracks. Because of its beveled end faces, a "Hexcentric" can be placed lengthwise as a wedge across a constricting section of a crack.
A more complicated camming chock than those described above is the "L.A.S. Split Cam Nut" marketed by Lowe Alpine Systems, Boulder, Colo., which includes a pair of parallel spaced, constant angle, toothed cam plates interconnected by a bolt carrying two orientation bars each with an eye at its free end for directly receiving a carabiner or a runner. When a force is applied to the orientation bar the cam teeth are pressed against the crack wall.